Exploring the metal flow and penetration fracture behavior is important for application of piercing extrusion process of solid ingot for high-performance seamless tube. A piercing extrusion process from solid ingot ( ) to titanium alloy tube ( ) has been studied in this paper. Based on FE soft of DEFORM-2D, a thermo-mechanical coupling model being able to describe the metal flow and penetration fracture behavior was developed for the piercing process of piercing extrusion of solid ingot. The piercing processes by using two kinds of piercing punches were analyzed. The results indicated that: at initial stage of piercing process, the deformation characteristic is similar to forward extrusion, and then metal reverse flows, and the backward extrusion is showed until the end cap is removed; the piercing force increases rapidly under forward extrusion, and backward extrusion occurs when the force rise to the stable value, the piercing force decreases rapidly at penetration fracture stage after removing the end cap; under backward extrusion, the piercing force has a little change by using cylindrical piercing punch, but the force will significantly increase again after a short stable stage by using bottle piercing punch, and thus the piercing force by using bottle piercing punch is more greater than that by using cylindrical piercing punch; at penetration fracture stage, fracture behavior by using cylindrical piercing punch is similar to that in blanking process, but the fracture face by using bottle piercing punch presents an approximate L-shaped.